Electron transport across glycerol monooleate bilayer lipid membranes facilitated by magnesium etiochlorin

Journal Article · Wed Apr 01 04:00:00 EST 1981 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(81)84842-4· OSTI ID:6569037

Feldberg, S W ^[1]; Armen, G H; Bell, J A; Chang, C K; Wang, C B

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1. Brookhaven National Lab., Upton, NY

The system described here comprises a glycerol monooleate bilayer lipid membrane (blm) containing a magnesium etiochlorin (Mg-C) separating two aqueous phases each containing ferricyanide, ferrocyanide, KCl, and a platinum electrode. The E/sup 0/s for the Mg-C/sup +//Mg-C and ferri-/ferrocyanide couples are 0.22 and 0.24 V vs. SCE. Thus the Mg-C/sup +//Mg-C system is easily poised by the ferri-/ferrocyanide system. When the potentials of the ferri-/ferrocyanide couples are different on each side of the blm we show that the open-circuit membrane potential nearly equals the difference between the redox potentials. This is unequivocal evidence that electrons are being transferred across the blm from one aqueous phase to the other. On the basis of these experiments we deduce that electron transport is the major charge transport mechanism. When redox potentials are the same on each side of the blm, the conductance of the membrane can be > 10/sup -3/S/cm/sup 2/. The conductance is proportional to the second power of the concentration of Mg-C in the membrane-forming mixture. A number of additional experiments are described which attempt to elucidate the mechanism of electron transfer. The data are consistent with the idea of an electron-hopping mechanism in which the transmembrane electron transport occurs by a series of second-order electron transfers between membrane-bound electron donors (Mg-C) and acceptors (Mg-C/sup +/). Alternative explanations are presented.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6569037
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 34:1; ISSN BIOJA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALKALINE EARTH METAL COMPOUNDS
BENCH-SCALE EXPERIMENTS
CARBOXYLIC ACIDS
CHLOROPHYLL
ELECTRON TRANSFER
GLYCEROL
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IN VITRO
MAGNESIUM COMPOUNDS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PORPHYRINS